This document describes a project on a smoke detector that was submitted by three students - M. Bharath Kumar, M. Sai Kumar, and P. Hari. It includes an introduction to smoke detectors, the working principle, block diagram, components used, code, advantages, and conclusion. The smoke detector circuit uses an MQ-2 smoke sensor and NodeMCU to detect smoke and display the smoke level on a LCD. When smoke is detected beyond a threshold, a buzzer sounds as an alarm. The project aims to easily detect smoke for protection purposes.

1. i
A project reports
On
SMOKE DETECTOR
Submitted by
M.BHARATH KUMAR 180069020
M.SAI KUMAR 180069021
P. HARI 180069023
Sec -1 Batch – 18
II/IV BACHELOR OF TECHNOLOGY
IN
Department of ELECTRICAL AND ELECTRONICS
ENGINEERING
K L UNIVERSITY: VADDESWARAM 522502
APRIL 2020

2. ii
K L UNIVERSITY
DEPARTMENT OF ELECTRICAL AND ELECTRONICS
ENGINEERING
Analog Electronics Circuit Design (18 EC 2103)
CERTIFICATE
This is to certify that Mr. M. BHARATH KUMAR – 180069020, Mr
. M.SAI KUMAR – 180069021, Mr. P. HARI – 180069023 of section 1
studying II/ IV B.Tech in EEE has satisfactorily completed
project SMOKE DETECTOR in the semester IV during the
academic year 2019 – 2020
COURSE INSTRUCTOR COURSE COORDINATOR
SIGNATURE OF HOD

3. iii
ACKNOWLEDGEMENT
We express great pleasure for me to express my gratitude to our honourable
President Sri. Koneru Satyanarayana, for providing the opportunity and
platform with facilities in accomplishing the project based laboratory. We express
the sincere gratitude to our principal Dr. k. Subbarao for his administration
and platform towards our academic growth.
We express sincere gratitude to our Head of the department EEE Dr. S. V.N.
LALITHA for her leadership and constant motivation provided in successful
completion of our academic semester. We record it as our privilege to deeply
thank for providing us the efficient faculty and facilities to make our ideas into
reality.
We express my sincere thanks to our project supervisor Mr. KASI UDAY
KIRAN for his novel association of ideas, encouragement, appreciation and
Intellectual zeal which motivated us to venture this project successfully.
We are pleased to acknowledge the indebtedness to our lab technicians who
devoted themselves directly or indirectly to make this project success.
Last but not least we express our deep gratitude and affection to our parents who
stood behind us in all our endeavours.
M.BHARATH KUMAR 180096020

4. iv
M.SAI KUMAR 180069021
P. HARI 180069023
INDEX
1 Abstract v
2 Introduction Vi
3 Principle vii
4 Block Diagram viii
5 Construction ix
6 Components Required X
7 Working xi-xxii
8 Code xxiii- xxiv
9 Advantages Xxv
10 Output Xxv

5. v
11 Conclusion xxvi
ABSTRACT
Approximation methods exist to provide estimates of smoke detector response
based on optical density, temperature rise, and gas velocity thresholds. The
objective of this study was to assess the uncertainty associated with three
estimation methods. Experimental data was used to evaluate recommended alarm
thresholds and to quantify the associated error. With few exceptions less than 50
percent of the predicted alarm times occurred within 60 seconds of the
experimental alarms. At best errors of 20 to 60 percent (in underprediction)
occurred for soldering fires using an optical density threshold. For flaming fires,
errors in predicted alarm times on the order of 100 to 1000 percent in over
prediction of the experimental alarms were common. Overall, none of the
approximation methods distinguished themselves as vastly supervisor. Great care
must be exercised when applying these approximation methods to ensure that
uncertainty in the predicted alarm times is appropriately considered.

6. vi
INTRODUCTION ABOUT THIS PROJECT
A smoke detector is a device that sense smoke, typically as an indicator of
fire. Commercial security devices issue a signal to a fire alarm control panel as a
part of a fire alarm system, while household smoke detectors, also known as
smoke alarms, generally issue a local audible or visual alarm from the detector
itself or several detectors if there are multiple smoke detectors interlinked.
Smoke detectors are housed in plastic enclousers, smoke detectors are typically
shaped like a disk or square about 150 millimeters (6 in) in diameter and 25
millimeters (1 in) thick, but shape and size vary. Smoke can be detected either
optically (photoelectric) or by physical process (ionization): detectors may use
either, or both, methods. Sensitive alarms can be used to detect, and thus deter,
smoking in areas where it is banned. Smoke detectors in large commercial,
industrial, and residential buildings are usually powered by a central fire alarm
system, which is powered by the building power with a battery backup. Domestic
smoke detectors range from individual battery-powered units, to several
interlinked mains-powered units with battery backup; with these interlinked units,
if any unit detects smoke, all trigger even if household power has gone out.
.

7. vii
PRINCIPLE:
The detector must be screwed to your ceiling because that's where smoke heads
for when something starts to burn. Fire generates hot gases and because these are
less dense (thinner—or weigh less per unit of volume) than ordinary air they rise
upward, swirling tiny smoke particles up too. As you can see in the photo up
above, the detector has slits around its case (1), which lead to the main detection
chamber. An invisible, infared light beam, similar to the ones that Tom Cruise
dodged, shoots into the chamber from a light-emitting diode (LED) (2). The
same chamber contains a photocell (3), which is an electronic light detector that
generates electricity when light falls on it. Normally, when there is no smoke
about, the light beam from the LED does not reach the detector. An electronic
circuit (4), monitoring the photocell, detects that all is well, and nothing happens.
The alarm (5) remains silent.
But if a fire breaks out, smoke enters the chamber (6) and scatters some of the
light beam (7) into the photocell (3). This triggers the circuit (8), setting off the
shrill and nasty alarm (9) that wakes you up and saves your life

8. viii
BLOCK DIAGRAM:
Simple Smoke Detector Alarm circuit using MQ02 designed with few easily
available components. Main part of this circuit is Gas sensor MQ-02 which is
capable of detecting Smoke, LPG, Propane and Hydrogen. It can be used in
different types of applications where the smoke and other mentioned gas leak
detection required.
The following prototype is a test circuit and it can be constructed through
breakout board and PCB after calibration of each components. This smoke
detector circuit will produce visible and audible alert when smoke detected.

9. ix
CONSTRUCTION :-

10. x
In this Smoke Detector Circuit with Arduino, we have used a MQ2 Gas Sensor
to detect preset smoke in the air. A 16x2 LCD is used for displaying the PPM
value of Smoke. And an LM358 IC for converting smoke sensor output into
digital form (this function is optional). A buzzer is placed as an alarm which gets
triggered when smoke level goes beyond 1000 PPM.
Circuit connections for this project are very simple, we have a Comparator
Circuit for comparing output voltage of smoke sensor with preset voltage (output
connected at pin D7). Also smoke sensor output is connected at an analog pin of
Arduino (A0). Buzzer is connected at Pin D9. And LCD connections are same as
Arduino LCD examples that are available in Arduino IDE (12, 11, 5, 4, 3, 2).
Remaining connections are shown in the circuit diagram.

11. xi
COMPONENTS REQUIRED: -
*NODEMCU
*Bread Board
*MQ-2 Smoke Sensor
*Jumper Wires
*Red Led
*Green Led
*Resistor
NODEMCU:
NodeMCU is an open-source electronics platform based on
easy-to-use hardware and software. Arduino boards are able to read
inputs - light on a sensor, a finger on a button, or a Twitter message
- and turn it into an output - activating a motor, turning on an LED,
publishing something online.
In this crystal ball project arduino is used to display the message on
the LCD according to the code written in the arduino software,
Whenever the tilt switch senses the moment of bread board and
sends the signals to the arduino.
MQ-2 SMOKE SENSOR: -

12. xii
Give your next Arduino project a nose for gasses with
the MQ2 Gas Sensor Module. This is a robust Gas sensor suitable for sensing
LPG, Smoke, Alcohol, Propane, Hydrogen, Methane and Carbon Mono xide
concentrations in the air. If you are planning on creating an indoor air quality
monitoring system; breath checker or early fire detection system, MQ2 Gas
Sensor Module is a great choice.
MQ2 is one of the commonly used gas sensors in MQ sensor series.
It is a Metal Oxide Semiconductor (MOS) type Gas Sensor also known as
Chemiresistors as the detection is based upon change of resistance of the sensing
material when the Gas comes in contact with the material. Using a simple voltage
divider network, concentrations of gas can be detected.
MQ-2 SENSOR
MQ2 Gas sensor works on 5V DC and draws around 800mW. It can detect LPG,
Smoke, Alcohol, Propane, Hydrogen, Methane and Carbon Monoxi de
concentrations anywhere from 200 to 10000ppm.
Here are the complete specifications

13. xiii
Operating Voltage 5v
Load Resistance 20 KΩ
Heater Resistance 33Ω ± 5%
Heating Consumption <800mw
Sensing Resistance 10 KΩ – 60 KΩ
Concentration Scope 200 – 10000ppm
Preheat Time Over 24 hours
Internal structure of MQ2 Gas Sensor
The sensor is actually enclosed in two layers of fine stainless steel mesh called
Anti-explosion network. It ensures that heater element inside the sensor will not
cause an explosion, as we are sensing flammable gases.
It also provides protection for the sensor and
filters out suspended particles so that only gaseous elements are able to pass inside
the chamber. The mesh is bound to rest of the body via a copper plated clamping
ring.

14. xiv
This is how the sensor looks like when outer mesh is
removed. The star-shaped structure is formed by the sensing element and six
connecting legs that extend beyond the Bakelite base. Out of six, two leads (H)
are responsible for heating the sensing element and are connected through
Nickel-Chromium coil, well known conductive alloy.
The remaining four leads (A & B) responsible for output signals are connected
using Platinum Wires. These wires are connected to the body of the sensing
element and convey small changes in the current that passes through the sensing
element.

15. xv
The tubular sensing element is made up of
Aluminum Oxide (AL2O3) based ceramic and has a coating of Tin Dioxide
(SnO2). The Tin Dioxide is the most important material being sensitive towards
combustible gases. However, the ceramic substrate merely increases heating
efficiency and ensures the sensor area is heated to a working temperature
constantly.

16. xvi
So, the Nickel-Chromium coil and Aluminum Oxide based ceramic forms
a Heating System; while Platinum wires and coating of Tin Dioxide forms a
Sensing System.
How does a gas sensor work?
When tin dioxide (semiconductor particles) is heated in air at high temperature,
oxygen is adsorbed on the surface. In clean air, donor electrons in tin dioxide are
attracted toward oxygen which is adsorbed on the surface of the sensing material.
This prevents electric current flow.
In the presence of reducing gases, the surface density of adsorbed oxygen
decreases as it reacts with the reducing gases. Electrons are then released into the
tin dioxide, allowing current to flow freely through the sensor
Hardware Overview – MQ2 Gas Sensor
Module
Since MQ2 Gas Sensor is not breadboard compatible, we do recommend this
handy little breakout board. It’s very easy to use and comes with two different
outputs. It not only provides a binary indication of the presence of combustible
gases but also an analog representation of their concentration in air.

17. xvii
The analog output voltage provided by the sensor changes in proportional to the
concentration of smoke/gas. The greater the gas concentration, the higher is the
output voltage; while lesser gas concentration results in low output voltage. The
following animation illustrates the relationship between gas concentration and
output voltage

18. xviii
VCC supplies power for the module. You can connect it to 5V output from your
Arduino.
GND is the Ground Pin and needs to be connected to GND pin on the Arduino.
D0 provides a digital representation of the presence of combustible gases.
A0 provides analog output voltage in proportional to the concentration of
smoke/gas.

19. xix
RESISTOR:
PASSIVE BUZZER:
A buzzer or beeper is an audio signalling device, which may be mechanical,
electromechanical, or piezoelectric (piezo for short). Typical uses of buzzers and
Beepers include alarm devices, timers, and confirmation of user input.

20. xx
JUMPER WIRES:
The term "jumper wire" simply refers to a conducting wire that establishes an
electrical connection between two points in a circuit. You can use jumper wires
to modify a circuit or to diagnose problems in a circuit. The following steps
outline how you can safely use jumper wires in different electrical applications.
Connecting Wires:
Connecting wires allows an electrical current to travel from one point on a circuit
to another because electricity needs a medium through which it can move. Most
of the connecting wires are made up of copper or aluminum.
In this crystal ball project connecting wires are used to connect the circuit.

21. xxi
WORKING
How does it Work?
The voltage that the sensor outputs changes accordingly to the smoke/gas level
that exists in the atmosphere. The sensor outputs a voltage that is proportional to
the concentration of smoke/gas.
In other words, the relationship between voltage and gas concentration is the
following:
• The greater the gas concentration, the greater the output voltage
• The lower the gas concentration, the lower the output voltage
The output can be an analog signal (A0) that can be read with an analog input of
the Arduino or a digital output (D0) that can be read with a digital input of the
Arduino.

22. xxii
Working Mechanism
Pin Wiring:
The MQ-2 sensor has 4 pins.
Pin-------------------------------------Wiring to Arduino Uno
A0-------------------------------------Analog pins
D0-------------------------------------Digital pins
GND-----------------------------------GND

23. xxiii
VCC-----------------------------------5V
---

24. xxiv
CODE
#include<ESP8266WiFi.h> String apikey=
"GWAZAQD8TU9F7AFC”. const
char*ssid="KL-UNIVERSITY4”. const
char*pass="“.
const char*server="api.thingspeak.com”.
WiFiClient Client. void
setup ()
{
Serial.begin(9600). delay (10).
WiFi.begin(ssid,pass); while
(WiFi.status()! =WL_CONNECTED)
{delay (500).
Serial.print(".").
}
Serial.println("").
Serial.println("WiFi CONNECTED").
} void loop
()
{
int gas=analogRead(A0).
gas=map(gas,0,1023,0,100). if
(Client.connect(server,80))
{
String poststr=apikey;
poststr+="&field= “.

25. xxv
25 poststr+=String(gas).
poststr="rnrn”.
Client.print("post/update HTTP/1.1n").
Client.print("Host: api.thingspeak.comn").
Client.print("connection:closen");
Client.print("x-THINGSPEAKAPIKEY:"+apikey+"n").
Client.print("content-length:").
Client.print(poststr.length());
Client.print("nn").
Client.print(poststr).
Serial.print("LPG GAS LEVEL IN %:").
Serial.println(gas).
}
Client.stop().
delay (500).
}

26. xxvi
ADVANTAGES: -
A. User friendly: we can edit the code whenever we want to change tone of the
button.
B. efficiency:it uses less power of only 5v.
C. portable: it is very small to carry wherever you go
D. Future Enhancement:
This technology could be further modified and more upgraded as per individual
need and interest. We have discussed some basic ideas of this technology. And
depending on innovative applications user can upgrade as per requirement.
• detection of low energy fires
• detection that is faster than heat detectors for most fires
• are preferred in life safety applications
OUTPUT: -
Hence the experiment of SMOKE DETECTOR is done by using MQ-2
smoke detecting sensor successfully and it is is displayed.

27. xxvii
CONCLUSION
This model can be used very easily instead of very large pianos and by installing
a few more components we can make it very lighter and very easier to play and
it will be very easier for the beginner in learning of piano.
• Smoke detector is one of the cheaper and easiest one.
• Most of industries use it, because it works fatly to protect, and it is most
effective.
• Using this we can easily detect the smoke.
• LDS provide the location of leakages without any persons a different place.